1. Field of the Invention
The present invention relates to a substrate having a fine line, an electron beam substrate utilizing the same, and an image display apparatus employing the same.
2. Related Background Art
There are also known configurations in which a fine line is formed on a substrate. The fine line can be, for example, a cell partition wall between light-emitting cells in a plasma display panel, or a wiring (electrode) for driving a device on a substrate.
In the following there will be shown an example of forming a fine line as a wiring in an electron source substrate.
As the electron source, there is for example known a configuration utilizing a surface conduction electron-emitting device. FIGS. 13A and 13B are respectively a schematic plan view of an electron emitting device and a schematic cross-sectional view along a line 13B-13B in FIG. 13A.
As shown in FIGS. 13A and 13B, the electron emitting device is principally composed of an insulating substrate 200, electrodes 2, 3 formed by film formation on the substrate 200, an electron-emitting electroconductive film 7 formed by film formation so as to be electrically connected to the electrodes 2, 3, and an electron-emitting region 8 provided in the electron-emitting electroconductive film 7.
As an application of such electron-emitting device, there is known an image forming apparatus such as a display apparatus. FIG. 14 is a partially broken perspective view of an image forming apparatus (image display apparatus) utilizing the surface conduction electron-emitting device shown in FIGS. 13A and 13B.
As shown in FIG. 14, such image display apparatus is provided with a substrate 81, an outer frame 82 and a face plate 86 on which an image forming member (phosphor) 84 is provided, and such outer frame 82, substrate 81 and face plate 86 are sealed at the connecting portions thereof with an unrepresented adhesive material such as low-melting glass frit to constitute an envelope (hermetic container) 88 for maintaining the interior of the image display apparatus in vacuum state.
On the substrate 81, there is fixed a substrate 200 on which electron-emitting devices are formed. On the substrate 200, electron-emitting devices 74 are formed in a matrix arrange n×m, wherein n and m and positive integers at least equal to 2, and are suitably selected according to the desired number of display pixels.
Each electron-emitting device 74 is connected to a row-direction wiring 4 and a column-direction wiring 6, both consisting of electroconductive films. The wirings shown in FIG. 14 consist of n column-direction wirings 6 and m row-direction wirings 4 (also called “matrix wirings”). At the crossing region of the row-direction wiring 4 and the column-direction wiring 6 there is provided an unrepresented insulating layer to insulate the row-direction wiring 4 from the column-direction wiring.
In order to form the image display apparatus described above, it is necessary to form a plurality of the row-direction wirings 4 and the column-direction wirings 6.
For forming a plurality of the row-direction wirings 4 and the column-direction wirings 6, it is disclosed, for example in the Japanese Patent Application Laid-open No. 8-34110, to form the wiring composed of an electroconductive film by a printing technology that is relatively inexpensive and is capable of covering a large area without a vacuum apparatus or the like.
For such printing technology, there is usually employed screen printing.
In the screen printing technology, a plate having an aperture of the desired pattern is employed as a mask, and paste containing electroconductive particles such as metal particles is printed through the aperture of the mask onto a substrate constituting the object of printing and is then baked thereby obtaining an electroconductive wiring of the desired pattern.
Also in order to obtain a finer pattern or an improvement in the positional precision which are difficult to attain with the screen printing, there may also be employed a method of employing photosensitive metal paste formed by providing the paste with photosensitive property.
In the method employing such photosensitive metal paste, the photosensitive paste formed as a film on the substrate is exposed to light through a photomask having a desired wiring pattern and is then subjected to development and baking processes thereby forming an electroconductive wiring of the desired pattern.
Among the electron-emitting devices, in addition to the aforementioned surface conduction type electron-emitting device, there are also known, for example, a spint type electron-emitting device having a conical electron-emitting region, and a MIM type electron-emitting device. The electron-emitting device can be utilized as an image display device by a combination with a phosphor which emits light by the electrons emitted by such electron-emitting device. Among the image display devices, there is known, for example, an EL device in addition to the electron-emitting device. Also there is known a configuration in which a micromirror is utilized as an image display device and an image is displayed by integrating such micromirrors and controlling the light reflection by each of such micromirrors. Also there is already widely employed a configuration of utilizing liquid crystal as an image display device for displaying an image.
Another background technology is disclosed in the Japanese Utility Model Application Laid-open No. 5-38874, which discloses, for connecting mutually opposed two conductive films, a technology of superposing a resistive film with each end of the two conductive films. Also there is disclosed a technology of forming the end portion of the conductive film with a straight or curved folding line such as of a sawtooth shape, a comb-tooth shape or an undulating shape in order to prevent a rack in the resistive film at the stepped difference in the superposed region from growing into a large single crack.
Still another background technology is disclosed in the Japanese Patent Application Laid-open No. 8-315723 which discloses a configuration of forming a recess in the wiring and positioning a spacer in such recess.